fs/ocfs2/buffer_head_io.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* -*- mode: c; c-basic-offset: 8; -*-
   3  * vim: noexpandtab sw=8 ts=8 sts=0:
   4  *
   5  * io.c
   6  *
   7  * Buffer cache handling
   8  *
   9  * Copyright (C) 2002, 2004 Oracle.  All rights reserved.
  10  */
  11
  12 #include <linux/fs.h>
  13 #include <linux/types.h>
  14 #include <linux/highmem.h>
  15 #include <linux/bio.h>
  16
  17 #include <cluster/masklog.h>
  18
  19 #include "ocfs2.h"
  20
  21 #include "alloc.h"
  22 #include "inode.h"
  23 #include "journal.h"
  24 #include "uptodate.h"
  25 #include "buffer_head_io.h"
  26 #include "ocfs2_trace.h"
  27
  28 /*
  29  * Bits on bh->b_state used by ocfs2.
  30  *
  31  * These MUST be after the JBD2 bits.  Hence, we use BH_JBDPrivateStart.
  32  */
  33 enum ocfs2_state_bits {
  34         BH_NeedsValidate = BH_JBDPrivateStart,
  35 };
  36
  37 /* Expand the magic b_state functions */
  38 BUFFER_FNS(NeedsValidate, needs_validate);
  39
  40 int ocfs2_write_block(struct ocfs2_super *osb, struct buffer_head *bh,
  41                       struct ocfs2_caching_info *ci)
  42 {
  43         int ret = 0;
  44
  45         trace_ocfs2_write_block((unsigned long long)bh->b_blocknr, ci);
  46
  47         BUG_ON(bh->b_blocknr < OCFS2_SUPER_BLOCK_BLKNO);
  48         BUG_ON(buffer_jbd(bh));
  49
  50         /* No need to check for a soft readonly file system here. non
  51          * journalled writes are only ever done on system files which
  52          * can get modified during recovery even if read-only. */
  53         if (ocfs2_is_hard_readonly(osb)) {
  54                 ret = -EROFS;
  55                 mlog_errno(ret);
  56                 goto out;
  57         }
  58
  59         ocfs2_metadata_cache_io_lock(ci);
  60
  61         lock_buffer(bh);
  62         set_buffer_uptodate(bh);
  63
  64         /* remove from dirty list before I/O. */
  65         clear_buffer_dirty(bh);
  66
  67         get_bh(bh); /* for end_buffer_write_sync() */
  68         bh->b_end_io = end_buffer_write_sync;
  69         submit_bh(REQ_OP_WRITE, 0, bh);
  70
  71         wait_on_buffer(bh);
  72
  73         if (buffer_uptodate(bh)) {
  74                 ocfs2_set_buffer_uptodate(ci, bh);
  75         } else {
  76                 /* We don't need to remove the clustered uptodate
  77                  * information for this bh as it's not marked locally
  78                  * uptodate. */
  79                 ret = -EIO;
  80                 mlog_errno(ret);
  81         }
  82
  83         ocfs2_metadata_cache_io_unlock(ci);
  84 out:
  85         return ret;
  86 }
  87
  88 /* Caller must provide a bhs[] with all NULL or non-NULL entries, so it
  89  * will be easier to handle read failure.
  90  */
  91 int ocfs2_read_blocks_sync(struct ocfs2_super *osb, u64 block,
  92                            unsigned int nr, struct buffer_head *bhs[])
  93 {
  94         int status = 0;
  95         unsigned int i;
  96         struct buffer_head *bh;
  97         int new_bh = 0;
  98
  99         trace_ocfs2_read_blocks_sync((unsigned long long)block, nr);
 100
 101         if (!nr)
 102                 goto bail;
 103
 104         /* Don't put buffer head and re-assign it to NULL if it is allocated
 105          * outside since the caller can't be aware of this alternation!
 106          */
 107         new_bh = (bhs[0] == NULL);
 108
 109         for (i = 0 ; i < nr ; i++) {
 110                 if (bhs[i] == NULL) {
 111                         bhs[i] = sb_getblk(osb->sb, block++);
 112                         if (bhs[i] == NULL) {
 113                                 status = -ENOMEM;
 114                                 mlog_errno(status);
 115                                 break;
 116                         }
 117                 }
 118                 bh = bhs[i];
 119
 120                 if (buffer_jbd(bh)) {
 121                         trace_ocfs2_read_blocks_sync_jbd(
 122                                         (unsigned long long)bh->b_blocknr);
 123                         continue;
 124                 }
 125
 126                 if (buffer_dirty(bh)) {
 127                         /* This should probably be a BUG, or
 128                          * at least return an error. */
 129                         mlog(ML_ERROR,
 130                              "trying to sync read a dirty "
 131                              "buffer! (blocknr = %llu), skipping\n",
 132                              (unsigned long long)bh->b_blocknr);
 133                         continue;
 134                 }
 135
 136                 lock_buffer(bh);
 137                 if (buffer_jbd(bh)) {
 138 #ifdef CATCH_BH_JBD_RACES
 139                         mlog(ML_ERROR,
 140                              "block %llu had the JBD bit set "
 141                              "while I was in lock_buffer!",
 142                              (unsigned long long)bh->b_blocknr);
 143                         BUG();
 144 #else
 145                         unlock_buffer(bh);
 146                         continue;
 147 #endif
 148                 }
 149
 150                 get_bh(bh); /* for end_buffer_read_sync() */
 151                 bh->b_end_io = end_buffer_read_sync;
 152                 submit_bh(REQ_OP_READ, 0, bh);
 153         }
 154
 155 read_failure:
 156         for (i = nr; i > 0; i--) {
 157                 bh = bhs[i - 1];
 158
 159                 if (unlikely(status)) {
 160                         if (new_bh && bh) {
 161                                 /* If middle bh fails, let previous bh
 162                                  * finish its read and then put it to
 163                                  * aovoid bh leak
 164                                  */
 165                                 if (!buffer_jbd(bh))
 166                                         wait_on_buffer(bh);
 167                                 put_bh(bh);
 168                                 bhs[i - 1] = NULL;
 169                         } else if (bh && buffer_uptodate(bh)) {
 170                                 clear_buffer_uptodate(bh);
 171                         }
 172                         continue;
 173                 }
 174
 175                 /* No need to wait on the buffer if it's managed by JBD. */
 176                 if (!buffer_jbd(bh))
 177                         wait_on_buffer(bh);
 178
 179                 if (!buffer_uptodate(bh)) {
 180                         /* Status won't be cleared from here on out,
 181                          * so we can safely record this and loop back
 182                          * to cleanup the other buffers. */
 183                         status = -EIO;
 184                         goto read_failure;
 185                 }
 186         }
 187
 188 bail:
 189         return status;
 190 }
 191
 192 /* Caller must provide a bhs[] with all NULL or non-NULL entries, so it
 193  * will be easier to handle read failure.
 194  */
 195 int ocfs2_read_blocks(struct ocfs2_caching_info *ci, u64 block, int nr,
 196                       struct buffer_head *bhs[], int flags,
 197                       int (*validate)(struct super_block *sb,
 198                                       struct buffer_head *bh))
 199 {
 200         int status = 0;
 201         int i, ignore_cache = 0;
 202         struct buffer_head *bh;
 203         struct super_block *sb = ocfs2_metadata_cache_get_super(ci);
 204         int new_bh = 0;
 205
 206         trace_ocfs2_read_blocks_begin(ci, (unsigned long long)block, nr, flags);
 207
 208         BUG_ON(!ci);
 209         BUG_ON((flags & OCFS2_BH_READAHEAD) &&
 210                (flags & OCFS2_BH_IGNORE_CACHE));
 211
 212         if (bhs == NULL) {
 213                 status = -EINVAL;
 214                 mlog_errno(status);
 215                 goto bail;
 216         }
 217
 218         if (nr < 0) {
 219                 mlog(ML_ERROR, "asked to read %d blocks!\n", nr);
 220                 status = -EINVAL;
 221                 mlog_errno(status);
 222                 goto bail;
 223         }
 224
 225         if (nr == 0) {
 226                 status = 0;
 227                 goto bail;
 228         }
 229
 230         /* Don't put buffer head and re-assign it to NULL if it is allocated
 231          * outside since the caller can't be aware of this alternation!
 232          */
 233         new_bh = (bhs[0] == NULL);
 234
 235         ocfs2_metadata_cache_io_lock(ci);
 236         for (i = 0 ; i < nr ; i++) {
 237                 if (bhs[i] == NULL) {
 238                         bhs[i] = sb_getblk(sb, block++);
 239                         if (bhs[i] == NULL) {
 240                                 ocfs2_metadata_cache_io_unlock(ci);
 241                                 status = -ENOMEM;
 242                                 mlog_errno(status);
 243                                 /* Don't forget to put previous bh! */
 244                                 break;
 245                         }
 246                 }
 247                 bh = bhs[i];
 248                 ignore_cache = (flags & OCFS2_BH_IGNORE_CACHE);
 249
 250                 /* There are three read-ahead cases here which we need to
 251                  * be concerned with. All three assume a buffer has
 252                  * previously been submitted with OCFS2_BH_READAHEAD
 253                  * and it hasn't yet completed I/O.
 254                  *
 255                  * 1) The current request is sync to disk. This rarely
 256                  *    happens these days, and never when performance
 257                  *    matters - the code can just wait on the buffer
 258                  *    lock and re-submit.
 259                  *
 260                  * 2) The current request is cached, but not
 261                  *    readahead. ocfs2_buffer_uptodate() will return
 262                  *    false anyway, so we'll wind up waiting on the
 263                  *    buffer lock to do I/O. We re-check the request
 264                  *    with after getting the lock to avoid a re-submit.
 265                  *
 266                  * 3) The current request is readahead (and so must
 267                  *    also be a caching one). We short circuit if the
 268                  *    buffer is locked (under I/O) and if it's in the
 269                  *    uptodate cache. The re-check from #2 catches the
 270                  *    case that the previous read-ahead completes just
 271                  *    before our is-it-in-flight check.
 272                  */
 273
 274                 if (!ignore_cache && !ocfs2_buffer_uptodate(ci, bh)) {
 275                         trace_ocfs2_read_blocks_from_disk(
 276                              (unsigned long long)bh->b_blocknr,
 277                              (unsigned long long)ocfs2_metadata_cache_owner(ci));
 278                         /* We're using ignore_cache here to say
 279                          * "go to disk" */
 280                         ignore_cache = 1;
 281                 }
 282
 283                 trace_ocfs2_read_blocks_bh((unsigned long long)bh->b_blocknr,
 284                         ignore_cache, buffer_jbd(bh), buffer_dirty(bh));
 285
 286                 if (buffer_jbd(bh)) {
 287                         continue;
 288                 }
 289
 290                 if (ignore_cache) {
 291                         if (buffer_dirty(bh)) {
 292                                 /* This should probably be a BUG, or
 293                                  * at least return an error. */
 294                                 continue;
 295                         }
 296
 297                         /* A read-ahead request was made - if the
 298                          * buffer is already under read-ahead from a
 299                          * previously submitted request than we are
 300                          * done here. */
 301                         if ((flags & OCFS2_BH_READAHEAD)
 302                             && ocfs2_buffer_read_ahead(ci, bh))
 303                                 continue;
 304
 305                         lock_buffer(bh);
 306                         if (buffer_jbd(bh)) {
 307 #ifdef CATCH_BH_JBD_RACES
 308                                 mlog(ML_ERROR, "block %llu had the JBD bit set "
 309                                                "while I was in lock_buffer!",
 310                                      (unsigned long long)bh->b_blocknr);
 311                                 BUG();
 312 #else
 313                                 unlock_buffer(bh);
 314                                 continue;
 315 #endif
 316                         }
 317
 318                         /* Re-check ocfs2_buffer_uptodate() as a
 319                          * previously read-ahead buffer may have
 320                          * completed I/O while we were waiting for the
 321                          * buffer lock. */
 322                         if (!(flags & OCFS2_BH_IGNORE_CACHE)
 323                             && !(flags & OCFS2_BH_READAHEAD)
 324                             && ocfs2_buffer_uptodate(ci, bh)) {
 325                                 unlock_buffer(bh);
 326                                 continue;
 327                         }
 328
 329                         get_bh(bh); /* for end_buffer_read_sync() */
 330                         if (validate)
 331                                 set_buffer_needs_validate(bh);
 332                         bh->b_end_io = end_buffer_read_sync;
 333                         submit_bh(REQ_OP_READ, 0, bh);
 334                         continue;
 335                 }
 336         }
 337
 338 read_failure:
 339         for (i = (nr - 1); i >= 0; i--) {
 340                 bh = bhs[i];
 341
 342                 if (!(flags & OCFS2_BH_READAHEAD)) {
 343                         if (unlikely(status)) {
 344                                 /* Clear the buffers on error including those
 345                                  * ever succeeded in reading
 346                                  */
 347                                 if (new_bh && bh) {
 348                                         /* If middle bh fails, let previous bh
 349                                          * finish its read and then put it to
 350                                          * aovoid bh leak
 351                                          */
 352                                         if (!buffer_jbd(bh))
 353                                                 wait_on_buffer(bh);
 354                                         put_bh(bh);
 355                                         bhs[i] = NULL;
 356                                 } else if (bh && buffer_uptodate(bh)) {
 357                                         clear_buffer_uptodate(bh);
 358                                 }
 359                                 continue;
 360                         }
 361                         /* We know this can't have changed as we hold the
 362                          * owner sem. Avoid doing any work on the bh if the
 363                          * journal has it. */
 364                         if (!buffer_jbd(bh))
 365                                 wait_on_buffer(bh);
 366
 367                         if (!buffer_uptodate(bh)) {
 368                                 /* Status won't be cleared from here on out,
 369                                  * so we can safely record this and loop back
 370                                  * to cleanup the other buffers. Don't need to
 371                                  * remove the clustered uptodate information
 372                                  * for this bh as it's not marked locally
 373                                  * uptodate. */
 374                                 status = -EIO;
 375                                 clear_buffer_needs_validate(bh);
 376                                 goto read_failure;
 377                         }
 378
 379                         if (buffer_needs_validate(bh)) {
 380                                 /* We never set NeedsValidate if the
 381                                  * buffer was held by the journal, so
 382                                  * that better not have changed */
 383                                 BUG_ON(buffer_jbd(bh));
 384                                 clear_buffer_needs_validate(bh);
 385                                 status = validate(sb, bh);
 386                                 if (status)
 387                                         goto read_failure;
 388                         }
 389                 }
 390
 391                 /* Always set the buffer in the cache, even if it was
 392                  * a forced read, or read-ahead which hasn't yet
 393                  * completed. */
 394                 ocfs2_set_buffer_uptodate(ci, bh);
 395         }
 396         ocfs2_metadata_cache_io_unlock(ci);
 397
 398         trace_ocfs2_read_blocks_end((unsigned long long)block, nr,
 399                                     flags, ignore_cache);
 400
 401 bail:
 402
 403         return status;
 404 }
 405
 406 /* Check whether the blkno is the super block or one of the backups. */
 407 static void ocfs2_check_super_or_backup(struct super_block *sb,
 408                                         sector_t blkno)
 409 {
 410         int i;
 411         u64 backup_blkno;
 412
 413         if (blkno == OCFS2_SUPER_BLOCK_BLKNO)
 414                 return;
 415
 416         for (i = 0; i < OCFS2_MAX_BACKUP_SUPERBLOCKS; i++) {
 417                 backup_blkno = ocfs2_backup_super_blkno(sb, i);
 418                 if (backup_blkno == blkno)
 419                         return;
 420         }
 421
 422         BUG();
 423 }
 424
 425 /*
 426  * Write super block and backups doesn't need to collaborate with journal,
 427  * so we don't need to lock ip_io_mutex and ci doesn't need to bea passed
 428  * into this function.
 429  */
 430 int ocfs2_write_super_or_backup(struct ocfs2_super *osb,
 431                                 struct buffer_head *bh)
 432 {
 433         int ret = 0;
 434         struct ocfs2_dinode *di = (struct ocfs2_dinode *)bh->b_data;
 435
 436         BUG_ON(buffer_jbd(bh));
 437         ocfs2_check_super_or_backup(osb->sb, bh->b_blocknr);
 438
 439         if (ocfs2_is_hard_readonly(osb) || ocfs2_is_soft_readonly(osb)) {
 440                 ret = -EROFS;
 441                 mlog_errno(ret);
 442                 goto out;
 443         }
 444
 445         lock_buffer(bh);
 446         set_buffer_uptodate(bh);
 447
 448         /* remove from dirty list before I/O. */
 449         clear_buffer_dirty(bh);
 450
 451         get_bh(bh); /* for end_buffer_write_sync() */
 452         bh->b_end_io = end_buffer_write_sync;
 453         ocfs2_compute_meta_ecc(osb->sb, bh->b_data, &di->i_check);
 454         submit_bh(REQ_OP_WRITE, 0, bh);
 455
 456         wait_on_buffer(bh);
 457
 458         if (!buffer_uptodate(bh)) {
 459                 ret = -EIO;
 460                 mlog_errno(ret);
 461         }
 462
 463 out:
 464         return ret;
 465 }